New AllerGen research that aims to understand the effects of traffic pollution on the lungs has shown that two hours of exposure to diesel exhaust causes an enhanced allergic response in sensitized individuals, particularly in those who are genetically susceptible.

“Diesel exhaust is a model of traffic-related air pollution which we showed, at levels common to highly-polluted cities, augmented an allergen-induced increase in airway eosinophil number and activity,” says Dr. Carlsten. “Those with a genetic trait associated with deficiency in the response to oxidative stress were particularly prone to the augmented responses to diesel exhaust-allergen co-exposure.”

In the novel study design, 18 participants were assessed for sensitization to an allergen, then exposed to each of filtered air or diesel exhaust for a period of two hours followed closely by a challenge with the allergen to which they were sensitive. Two days after exposure, airway samples were collected and analyzed for markers of allergic inflammation (eosinophils, Th2, cytokines) and immune cell activation.

The study also found that individuals with a genetic predisposition to allergic disease (GSTT1 null) were particularly susceptible to the effects of co-exposure to inhaled diesel exhaust and an allergen.

“Our findings are important given how commonly co-exposure to allergen and traffic-related air pollution occurs,” says Dr. Carlsten. “We believe that embracing, rather than ignoring, the multi-layered complexity of these dynamics—multiple exposures and the additional effect of gene variants—is critical to a robust understanding and, ultimately, remediation of these and other problematic exposures.”